Question: $58.3 \times 89 =$
${5}$ ${8}$ ${3}$ ${8}$ ${9}$ ${\times\vphantom{0}}$ ${.}$ ${0.3}\times {9}= {2.7}$ ${7}$ ${8}\times {9}+C{2}= {74}$ ${4}$ ${50}\times {9}+C{70}= {520}$ ${2}$ ${5}$ ${0.3}\times {80}= {24}$ ${4}$ ${0}$ ${8}\times {80}+C{20}= {660}$ ${6}$ ${50}\times {80}+C{600}= {4600}$ ${6}$ ${4}$ ${+\vphantom{0}}$ ${5}$ ${1}$ ${8}$ ${8}$ ${7}$ ${+\vphantom{0}}$ ${5}$ ${1}$ ${8}$ ${8}$ ${7}$ ${.}$ The top number has $1$ digit to the right of the decimal. The bottom number has $0$ digits to the right of the decimal. The product has $1+0=1$ digit to the right of the decimal. $58.3 \times 89 = 5188.7$